INVE Aquaculture organizes Technical Seminar at Ongole, Andhra Pradesh

Inve Asia Services Ltd., organized a one day Technical Seminar for the benefit of Shrimp farmers of South Andhra Pradesh at Hotel Sarovar, Ongole on 31st January 2018. The key speakers at the event were Dr. Oliver Decamp, Farm and Feedmill Product Manager, INVE Aquaculture who spoke on “Improved Farming Practices for better Shrimp Disease Management”, and Mr. Manuel Paulain, Key Accounts Manager, INVE Asia Services Ltd., who delivered a lecture on “New Paradigms in Indoor shrimp farming – an Asian experience”.

Dr. Olivier Decamp, in his presentation pointed out that historically, viruses were responsible for the majority of financial losses in Shrimp Aquaculture. However, the situation had changed with AHPND (Early Mortality Syndrome), a bacterial disease that is responsible for losses of over 1 billion USD in Asia since 2009, and EHP, a microsporidian parasite affecting growth rate and causing size variation in farmed shrimp.

When faced with a new disease, the first step is to have a thorough understanding of the causative agent and factors associated with it. Looking at Early Mortality Syndrome, it involved the identification of the pathogen (specific virulent strains of Vibrio parahaemolyticus), and then understanding the disease. This meant identifying the point of entry of the pathogen, live feed for broodstock, contaminated postlarvae and contaminated sediment in farm. Next, it required a better understanding of the complexity of the disease. For example, it was shown that the genes associated with the disease may be transferred to other species of Vibrio. The hatchery and farm management required a control of Vibrio in general, rather than a specific strain of V. parahaemolyticus. For syndromes where the exact cause is not confirmed, such as white faeces, it meant identifying all likely causes and setting up plans to control them.

Taking all these uncertainties into consideration, farmers have focussed on biosecurity, improved nutrition in critical culture stages and ways to control the accumulation of organic waste. Biosecurity protocols are well known but their consistent implementation can be challenging. The recent disease outbreaks have forced the sector to (1) include screening protocols for broodstock, diet/feed, nauplii and postlarvae; (2) disinfect eggs, nauplii and postlarvae; and (3) use disinfection procedures that are more efficient against Vibrio biofilm.

The control of Vibrio during shrimp larviculture relies on (1) protocols to maintain hygiene of algae and artemia; (2) use of probiotics to degrade the organic waste and to compete with vibrios. The success of these approaches has been documented in numerous peerreviewed publications and in field trials worldwide.

The production cycle from PL10 to harvest size was badly affected by the recent disease outbreak. As a consequence, farmers looked at better ways to manage this critical phase, and many decided to invest in a nursery system. After investigating the various shrimp nursery designs in Latin America and Asia, farmers built systems that were adapted to their business model. There are different objectives for the shrimp nursery. It can be used for acclimating and screening animals before stocking. In this case, farmers may disinfect the shrimp, and treat them with health booster products or probiotics to strengthen them before stocking. Other farmers focus on growing animals to be stronger and reduce the duration of the production cycle in the open pond. This requires bigger investment but does reduce the loss during the first 3-4 weeks of cycle. Some farmers, who have access to large volume of treated water, rely on high water exchange to control organic waste and ammonia. Typically, they use high quality diet to boost growth rates. Farmers, who have less access to treated water, operate their nursery with very limited water exchange to control the entry of pathogens. . This system requires maturing of water and frequent application of probiotics.

Finally, in the grow-out pond, the need to reduce the accumulation of organic waste to control vibrios has led to (1) investment in high water exchange systems where each shrimp pond is linked to numerous water treatment ponds; or (2) investment in quality water and feed probiotics to degrade the organic waste and manage the microbial community.

The conclusions are:

  • To prevent vertical transmission of pathogens from broodstock to nauplii, then to postlarvae and finally juveniles
  •  To focus on key pathogens, vibrio and EHP, without ignoring WSSV
  • To adapt pond management in such a way that the reinfection of shrimps with the pathogens present in waste is prevented
  • To enhance the nutritional quality (quality diet), health (health booster and feed probiotics) and environment (waste control and microbial management)

Mr. Manuel Poulain presented INVE’s views on indoor shrimp farming which focused on microbial management via environmental control. High density nurseries show high productivity due to constant application of high quality probiotics and the use of superior enriched diets.

The protocol for minimizing water exchange and enhancing biosecurity involved the following steps;

The process starts with a proper disinfection of the tank/pond/material via 1% spray application of PUR, to completely remove all biofilms. Directly after water fill-up, microbial management is enhanced by the application of 20.000 CFU/ml of probiotic bacteria, followed with a standard application of 10.000 CFU/ml every 5 days. The product used is the Pro-W, which through its very high concentration of 50 billion cell/g of product makes this application economically reasonable.

Microbial management depends upon environmental control, in which INVE’s approach is multitrophic: It considers the enhancement of chemoautotrophic organisms within the system (or nitrifiers), together with the limitation of the photoautotroph organisms (phytoplankton) through the installation of a shadecloth or membrane over the tanks/ponds. The constant addition of probiotic to the water (Pro-W) and animals (Pro-2) plays a major role in the competitive exclusion of pathogenic and opportunistic bacteria such as Vibrio sp. This last part concerns heterotrophic organism balance, last piece of the multitrophic approach aspect.

On the other side, protocols include boosters for the shrimp health and overall defence system, with the addition of the S-Pak feed supplement, and Top-S feed top-coating. INVE suggests application of 15 to 30% of the total daily feed in S-Pak. This high quality diet is enriched with elevated doses of nutraceuticals and specific components to boost the shrimp overall immune system. The S-Pak is given to the shrimp as a whole during the first feed distribution of the day, as breakfast for the animals. When the S-Pak is stopped, the immunostimulant additions are replaced with Top-S, as a feed top coating.

The application of these techniques in Vietnam farms over the past years resulted in a minimum saving of 15 – 30% in the cost of nursery operations. Biosecurity increased by a factor of 3, simply due to the reduction of water exchange of about 300% total water renewal over a 30 days nursery period, to below 100%.

The cost of probiotics and feed supplement is compensated by a much lower cost for water pumping, together with lower use of water treatment products, and lesser manpower required for operating the nursery. Lower water exchanges also allows a higher control of the microbial communities in action (multi-trophic approach), and an optimal balance of biochemical reactions at stake, such as nitrification processes and bacterial competitive exclusion. Mr. Poulain added that the INVE nursery approach focused on risk management to achieve more consistent results, creating a higher predictability of outputs, sustaining a more robust business model.

The seminar had a participation of over 60 delegates that included Corporate farms, small to medium farmers, technical consultants and feed/chemical dealers.



Source : Aquaculture Spectrum

Leave a Reply

Your email address will not be published. Required fields are marked *